KR102013535B1 - Method for Preparing Polyimide Precursor Composition With Improved Storage Stability and Viscosity Stability, and Polyimide Precursor Composition Prepared by Using the Same - Google Patents

Abstract

Provided is a method for preparing a polyimide precursor composition comprising the following steps: (a) preparing a polyamic acid solution by polymerizing a diamine monomer and a dianhydride monomer at a mole ratio of 1 : 0.98 to 0.99 in an organic solvent; and (b) raising the temperature of the polyamic acid solution at 55 to 85 °C, stirring the same for 1 to 4 hours and aging the same.

Description

Method for Preparing Polyimide Precursor Composition Improved Storage Stability and Viscosity Stability, Method for Preparing Polyimide Precursor Composition With Improved Storage Stability and Viscosity Stability, and Polyimide Precursor Composition Prepared by Using the Same}

The present invention relates to a method for preparing a polyimide precursor composition having improved storage stability and viscosity stability, and a polyimide precursor composition prepared using the same.

Polyimide (PI) is a polymer material having thermal stability based on a rigid aromatic backbone, and has mechanical properties such as excellent strength, chemical resistance, weather resistance, and heat resistance based on the chemical stability of an imide ring.

In addition, polyimide has been spotlighted as a high-performance polymer material applicable to a wide range of industrial fields such as electronics, communication, and optics due to its excellent electrical properties such as insulation and low dielectric constant.

Recently, as various electronic devices become thinner, lighter and smaller, many studies have been conducted to use a thin and flexible polyimide film as a display substrate that can replace an insulating material of a circuit board or a glass substrate for a display. .

In general, a polyimide film is prepared by applying a polyamic acid produced by a polymerization reaction of dianhydride and diamine on a support and imidizing it to prepare a film, and peeling it from the support.

In this case, the polyamic acid includes both an amine group and a carboxylic acid group, and in particular, the hydroxy group in the carboxylic acid group may be hydrolyzed as it reacts with an adjacent amine group, resulting in poor storage stability and viscosity stability of the polyimide precursor composition including the same. Known. In addition, this phenomenon is known to stand out at room temperature or more than the low temperature.

When the storage stability and the viscosity stability of the polyimide precursor composition are poor, the viscosity may change greatly during the process or during the long-term thawing process, and thus the application and imidization of the polyimide precursor composition may proceed unstable. In addition, when the viscosity of the polyamic acid changes, it may cause a decrease in the mechanical and thermal properties of the polyimide film.

The degradation of the thermal properties of the double polyimide film can be particularly negative for the manufacture of display substrates involving high temperature processes.

For example, in the case of an organic light emitting diode (OLED) using a low temperature polysilane (LTPS) process, a process temperature of 400 ° C. or higher may be formed, and even at this high temperature, even a polyimide having excellent heat resistance may be thermally decomposed. The thermal properties of the mid film may be a very important factor for implementing the display substrate.

In addition, in the method of manufacturing a polyimide film as described above, a process of applying a polyamic acid on a support, followed by imidization to prepare a film in the form of a film, and a process of peeling it from the support are sequentially performed. It is common to produce a mid film, and in particular, when the viscosity of the polyamic acid changes in the state of being left in the process of applying the polyamic acid on the support, a problem may occur in which the thickness of the target polyimide film changes.

Therefore, there is a high need for a polyamic acid having excellent storage stability at room temperature and viscosity stability during processing, and a polyimide film having excellent mechanical and thermal properties.

It is an object of the present invention to provide a method for producing a polyimide precursor composition having excellent storage stability at room temperature and viscosity stability during a process of applying a polyamic acid on a support, and a polyimide precursor composition prepared using the same.

At the same time, the polyimide film prepared from the polyimide precursor composition of the present invention has a thermal decomposition temperature (Td) of 1% by weight of 560 ° C or higher, a thermal expansion coefficient of 5 ppm / ° C or lower, an elongation of 15% or higher, and a tensile strength. The strength may be at least 350 MPa and the thickness may be 10 to 20 μm. Such a polyimide film has an advantage of satisfying mechanical and thermal characteristics required for a flexible printed circuit board or a display substrate.

Therefore, the present invention has a substantial object to provide a specific embodiment thereof.

The present invention to achieve the above object,

(a) polymerizing a diamine monomer and a dianhydride monomer in an organic solvent in a molar ratio of 1: 0.98 to 0.99 to prepare a polyamic acid solution; And

(b) heating the polyamic acid solution to 55 to 85 ° C., and stirring the mixture for 1 to 4 hours to provide a method of preparing a polyimide precursor composition.

The present invention also provides a polyimide precursor composition prepared from the production method, the polyimide precursor composition is formed on a support and dried to prepare a gel film, and a method for producing a polyimide film to cure the gel film and the preparation therefrom It can provide the polyimide film which becomes.

The present invention can also provide an electronic device including the polyimide film.

Hereinafter, specific contents for the implementation thereof will be described herein.

Prior to this, terms or words used in the present specification and claims should not be construed as being limited to the common or dictionary meanings, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention.

Therefore, the configuration of the embodiments described herein is only one of the most preferred embodiments of the present invention and does not represent all of the technical idea of the present invention, various equivalents and modifications that may be substituted for them at the time of the present application It should be understood that examples may exist.

As used herein, the singular forms "a", "an" and "the" include plural forms unless the context clearly indicates otherwise. As used herein, the terms "comprise", "comprise" or "have" are intended to indicate that there is a feature, number, step, component, or combination thereof, that is, one or more other features, It should be understood that it does not exclude in advance the possibility of the presence or addition of numbers, steps, components, or combinations thereof.

As used herein, "dianhydrides" are intended to include precursors or derivatives thereof, which may technically not be dianhydrides, but nevertheless will react with diamines to form polyamic acids. This polyamic acid can be converted back to polyimide.

As used herein, "diamine" is intended to include precursors or derivatives thereof, which may not technically be diamines, but will nevertheless react with dianhydrides to form polyamic acids, which in turn Can be converted to mid.

Where an amount, concentration, or other value or parameter is given herein as an enumeration of ranges, preferred ranges, or preferred upper and preferred lower values, any pair of any upper range thresholds, whether or not a range is disclosed separately, or It is to be understood that this disclosure specifically discloses all ranges formed with a desired value and any lower range limit or desired value.

When a range of numerical values is mentioned herein, unless stated otherwise, the range is intended to include the endpoint and all integers and fractions within that range.

It is intended that the scope of the invention not be limited to the particular values mentioned when defining the range.

<Polyimide precursor composition and its manufacturing method>

Method for producing a polyimide precursor composition according to the present invention,

(a) polymerizing a diamine monomer and a dianhydride monomer in an organic solvent in a molar ratio of 1: 0.98 to 0.99 to prepare a polyamic acid solution; And

(b) heating the polyamic acid solution to 55 to 85 ° C., and stirring for 1 to 4 hours for aging.

In one specific example, the polymerization reaction in the step (a) may be carried out at 10 to 50 ℃, specifically 20 to 40 ℃.

In one specific example, the aging of step (b) may exert an effect of improving the room temperature storage stability of the polyimide precursor composition, as described below.

Specifically, the aging of step (b) includes the step of raising the polyamic acid solution to 55 to 85 ℃, more specifically 60 to 80 ℃, and stirring for 1 to 4 hours, specifically 2 to 3 hours When the temperature rising temperature and the stirring time are outside the range defined in the present invention, the storage stability of the polyimide precursor composition to be produced may be lowered. In particular, when the temperature rising temperature is too high, the solid content may be due to solvent evaporation. This may vary, which is undesirable as it may cause degradation of the mechanical and thermal properties of the polyimide film produced.

In one specific example, the method for preparing a polyimide precursor composition according to the present invention comprises the steps of (c) cooling the polyamic acid solution aged in step (b) to 10 to 30 ° C, specifically 15 to 25 ° C. It may further include, the cooling method is not particularly limited, it may be natural cooling as an example.

The dianhydride monomer that may be used in the preparation of the polyamic acid solution of the present invention may be an aromatic tetracarboxylic dianhydride, wherein the aromatic tetracarboxylic dianhydride is a pyromellitic dianhydride (or PMDA), 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (or BPDA), 2,3,3', 4'-biphenyltetracarboxylic dianhydride (or a-BPDA), Oxydiphthalic dianhydride (or ODPA), diphenylsulfone-3,4,3 ', 4'-tetracarboxylic dianhydride (or DSDA), bis (3,4-dicarboxyphenyl) sulfide dianhydride Lide, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, 2,3,3 ', 4'-benzophenone Tetracarboxylic dianhydride, 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride (or BTDA), bis (3,4-dicarboxy Nil) methane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, p-phenylenebis (trimelitic monoester acid anhydride), p-biphenylene Bis (trimelitic monoester acid anhydride), m-terphenyl-3,4,3 ', 4'-tetracarboxylic dianhydride, p-terphenyl-3,4,3', 4 ' Tetracarboxylic dianhydride, 1,3-bis (3,4-dicarboxyphenoxy) benzene dianhydride, 1,4-bis (3,4-dicarboxyphenoxy) benzene dianhydride, 1 , 4-bis (3,4-dicarboxyphenoxy) biphenyl dianhydride, 2,2-bis [(3,4-dicarboxyphenoxy) phenyl] propane dianhydride (BPADA), 2,3 , 6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 4,4 '-(2,2-hexafluoroisopropylidene) diphthalic acid dianhydride Ride The are exemplified.

These may be used alone or in combination of two or more as desired, but dianhydride monomers which may be particularly preferably used in the present invention are pyromellitic dianhydride (PMDA), 3,3 ', 4,4 At least one selected from the group consisting of '-biphenyltetracarboxylic dianhydride (s-BPDA) and 2,3,3', 4'-biphenyltetracarboxylic dianhydride (a-BPDA) Can be.

In addition, the diamine monomer which can be used for manufacture of the polyamic-acid solution of this invention is an aromatic diamine, classified as follows, For example.

1) 1,4-diaminobenzene (or paraphenylenediamine, PDA), 1,3-diaminobenzene, 2,4-diaminotoluene, 2,6-diaminotoluene, 3,5-diaminobenzo Diamines having one benzene nucleus in structure, such as Ik acid (or DABA) and the like, diamines having a relatively rigid structure;

2) diaminodiphenyl ethers such as 4,4'-diaminodiphenyl ether (or oxydianiline, ODA), 3,4'-diaminodiphenyl ether, and 4,4'-diaminodiphenylmethane (Methylenediamine), 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'-bis (trifluoromethyl ) -4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-dicarboxy-4,4'-diaminodiphenylmethane , 3,3 ', 5,5'-tetramethyl-4,4'-diaminodiphenylmethane, bis (4-aminophenyl) sulfide, 4,4'-diaminobenzanilide, 3,3' -Dichlorobenzidine, 3,3'-dimethylbenzidine (or o-tolidine), 2,2'-dimethylbenzidine (or m-tolidine), 3,3'-dimethoxybenzidine, 2,2'-dimethoxy Benzidine, 3,3'-diaminodiphenylether, 3,4'-diaminodiphenylether, 4,4'-diaminodiphenylether, 3,3'-diaminodiphenylsulfide, 3,4 ' -Diaminodiphenylsulfide, 4,4'-diamino Phenylsulfide, 3,3'-diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, 3,3'-diaminobenzophenone, 4,4 ' -Diaminobenzophenone, 3,3'-diamino-4,4'-dichlorobenzophenone, 3,3'-diamino-4,4'-dimethoxybenzophenone, 3,3'-diaminodiphenyl Methane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 2,2-bis (3-aminophenyl) propane, 2,2-bis (4-amino Phenyl) propane, 2,2-bis (3-aminophenyl) -1,1,1,3,3,3-hexafluoropropane, 2,2-bis (4-aminophenyl) -1,1 , 1,3,3,3-hexafluoropropane, 3,3'-diaminodiphenylsulfoxide, 3,4'-diaminodiphenylsulfoxide, 4,4'-diaminodiphenylsulfoxide Diamines having two benzene nuclei in structure, and the like;

3) 1,3-bis (3-aminophenyl) benzene, 1,3-bis (4-aminophenyl) benzene, 1,4-bis (3-aminophenyl) benzene, 1,4-bis (4-amino Phenyl) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (3-aminophenoxy) benzene (or TPE-Q), 1,4-bis (4-aminophenoxy) Benzene (or TPE-Q), 1,3-bis (3-aminophenoxy) -4-trifluoromethylbenzene, 3,3'-diamino-4- (4-phenyl) phenoxybenzophenone, 3 , 3'-diamino-4,4'-di (4-phenylphenoxy) benzophenone, 1,3-bis (3-aminophenylsulfide) benzene, 1,3-bis (4-aminophenylsulfide) Benzene, 1,4-bis (4-aminophenylsulfide) benzene, 1,3-bis (3-aminophenylsulfone) benzene, 1,3-bis (4-aminophenylsulfone) benzene, 1,4-bis ( 4-aminophenylsulfone) benzene, 1,3-bis [2- (4-aminophenyl) isopropyl] benzene, 1,4-bis [2- (3-aminophenyl) isopropyl] benzene, 1,4- Having three benzene nuclei in structure, such as bis [2- (4-aminophenyl) isopropyl] benzene Amine;

4) 3,3'-bis (3-aminophenoxy) biphenyl, 3,3'-bis (4-aminophenoxy) biphenyl, 4,4'-bis (3-aminophenoxy) biphenyl, 4,4'-bis (4-aminophenoxy) biphenyl, bis [3- (3-aminophenoxy) phenyl] ether, bis [3- (4-aminophenoxy) phenyl] ether, bis [4- (3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] ether, bis [3- (3-aminophenoxy) phenyl] ketone, bis [3- (4-aminophenoxy C) phenyl] ketone, bis [4- (3-aminophenoxy) phenyl] ketone, bis [4- (4-amino phenoxy) phenyl] ketone, bis [3- (3-aminophenoxy) phenyl] sulfide , Bis [3- (4-aminophenoxy) phenyl] sulfide, bis [4- (3-aminophenoxy) phenyl] sulfide, bis [4- (4-aminophenoxy) phenyl] sulfide, bis [3- (3-aminophenoxy) phenyl] sulfone, bis [3- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (4-ami) Phenoxy) phenyl] sulfone, bis [3- (3-aminophenoxy) phenyl] methane, bis [3- (4-aminophenoxy) phenyl] methane, bis [4- (3-aminophenoxy) Phenyl] methane, bis [4- (4-aminophenoxy) phenyl] methane, 2,2-bis [3- (3-aminophenoxy) phenyl] propane, 2,2-bis [3- ( 4-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane (BAPP), 2,2-bis [3- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 2,2-bis [3- (4 -Aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 2,2-bis [4- (3-aminophenoxy) phenyl] -1,1,1, Such as 3,3,3-hexafluoropropane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, and the like, Diamine with four benzene nuclei in structure.

These may be used alone or in combination of two or more as desired, but the diamine monomers which may be particularly preferably used in the present invention include 4-diaminobenzene (PPD) and 1,3-diaminobenzene (MPD). , 2,4-diaminotoluene, 2,6-diaminotoluene and 3,5-diaminobenzoic acid (DABA) may be one or more selected from the group consisting of.

The organic solvent used in the present invention is not particularly limited as long as it is an organic solvent in which polyamic acid can be dissolved, but may be an aprotic polar solvent as one example.

Non-limiting examples of the aprotic polar solvent include amide solvents such as N, N'-dimethylformamide (DMF) and N, N'-dimethylacetamide (DMAc), p-chlorophenol, o-chloro Phenol solvents such as phenol, N-methyl-pyrrolidone (NMP), gamma butyrolactone (GBL), and Diglyme (Diglyme), and the like. These may be used alone or in combination of two or more thereof.

In some cases, the solubility of the polyamic acid may be adjusted by using auxiliary solvents such as toluene, tetrahydrofuran, acetone, methyl ethyl ketone, methanol, ethanol and water.

In one example, the organic solvent which may be particularly preferably used for the organic solvent may be N-methyl-pyrrolidone (NMP).

Meanwhile, a filler may be added to the “process of preparing a polyimide precursor composition” for the purpose of improving various properties of a film such as sliding, thermal conductivity, conductivity, corona resistance, and loop hardness. The filler to be added is not particularly limited, but preferred examples thereof include silica, titanium oxide, alumina, silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, mica and the like.

The particle size of the filler is not particularly limited and can be determined according to the film properties to be modified and the type of filler to be added. In general, the average particle diameter is 0.05 to 20 µm, preferably 0.1 to 10 µm, more preferably 0.1 to 5 µm, particularly preferably 0.1 to 3 µm.

If the particle size is less than this range, the modifying effect is less likely to appear. If the particle size is larger than this range, the surface properties may be largely impaired, or the mechanical properties may be greatly reduced.

The addition amount of the filler is not particularly limited, but may be determined by the film characteristics to be modified, the particle size of the filler, and the like. Generally, the addition amount of a filler is 0.01-10 weight part, Preferably it is 0.01-5 weight part, More preferably, it is 0.02-1 weight part with respect to 100 weight part of polyimide resins.

If the amount of filler added is less than this range, the effect of modification by the filler is less likely to appear, and if it exceeds this range, mechanical properties of the film may be largely impaired. The addition method of a filler is not specifically limited, Any known method can also be used.

On the other hand, the present invention provides a polyimide precursor composition prepared by a manufacturing method comprising the aging step, in one specific example, the polyimide precursor composition has a viscosity change of -300 cP to + 300 cP, specifically -200 cP to +200 cP.

Viscosity change = first viscosity-second viscosity (1)

Here, a 1st viscosity is an initial viscosity of a polyimide precursor composition at 25 degreeC, and a 2nd viscosity is a viscosity after 7 days passed at 25 degreeC.

Since the change in viscosity of the polyimide precursor composition means that the polyimide precursor composition has undergone denaturation, it can be understood as an index indicating the degree of modification of the polyimide precursor composition.

Conventional polyimic acid shows a viscosity change exceeding wh 300 cP when stored at room temperature for about 7 days, which means that a significant degree of denaturation has occurred in the polyamic acid. Mid film can be difficult to implement.

On the other hand, the polyimide precursor composition according to the present invention improves the room temperature storage stability of the polyimide precursor composition itself through the manufacturing method including the aging step, the viscosity change according to the formula is ㅁ 300 cP, in detail It can be seen that the storage stability at room temperature is very excellent as Wh 200 cP level.

The polydispersity index of the weight average molecular weight relative to the number average molecular weight of the polyamic acid included in the polyimide precursor composition by aging in the specific temperature range is 1,3 to 2,2, specifically 1.5 to 2.0. It can be understood that this is a controlled result.

Specifically, the adjustment of the ratio of the weight average molecular weight to the number average molecular weight of the polyamic acid as described above means that the distribution of the molecular weight is narrow, which means that the low molecular weight oligomers present in the polyimide precursor composition are relatively It can be understood that less is generated. That is, since it means that the number of low molecular weight oligomers that can cause a viscosity change through an additional polymerization reaction at room temperature, the polyimide precursor according to the present invention can exhibit the effect of improving the storage stability at room temperature.

In the present invention, the first viscosity may be 1,000 to 10,000 cP, specifically 2,000 to 9,000 cP, more specifically 3,000 to 8,000 cP, in one specific example, when the first viscosity is 3,000 to 8,000 cP The second viscosity may be 3,200 to 8,200 cP. The precursor composition of the present invention having the first viscosity in the above range has the advantage of easy handling in terms of fluidity, and may also be advantageous for film formation.

Specifically, when the viscosity of the polyimide precursor composition exceeds the above range, a higher pressure must be applied by friction with the pipe when the polyimide precursor composition is moved through the pipe during the polyimide manufacturing process. Process costs may be increased and handling may be degraded. In addition, the higher the viscosity, the more time and cost the mixing process can take.

On the other hand, when the viscosity of the polyimide precursor composition is less than the above range, the problem of increasing the manufacturing cost and processing time may occur as a large amount of solvent must be removed during the curing process.

In one specific example, the polyimide precursor composition may include 10 to 15% by weight solids based on the total weight.

When the solid content of the polyimide precursor composition exceeds the above range, it is unavoidable to increase the viscosity of the polyimide precursor composition, and on the contrary, the solid content of the polyimide precursor composition is less than the above range. In this case, since a large amount of solvent must be removed during the curing process, the manufacturing cost and processing time may increase, which is not preferable.

On the other hand, the production of a conventional polyamic acid solution, for example, by putting the whole amount of the diamine monomer in the solvent, and then adding the dianhydride monomer to substantially equal or molar excess of the diamine monomer and polymerization of the total amount of dianhydride monomer Is added to a solvent, and then a diamine monomer is added to be substantially equimolar or excess with the dianhydride monomer and polymerized.

As described above, the polyamic acid solution polymerized such that the diamine monomer or the dianhydride monomer is substantially equimolar or excessively defrosted and left for a long time at room temperature before use or left in the process of applying the polyamic acid described above on a support. When the viscosity of the polyamic acid changes in the process, a problem may occur that the thickness of the target polyimide film changes.

On the other hand, the present invention will be demonstrated in detail below, but to prepare a polyimide precursor composition by polymerizing the diamine monomer and dianhydride monomer in an organic solvent in a molar ratio of 1: 0.98 to 0.99, the polymerization in a specific molar ratio as described above Unlike the case where the polyimide precursor composition of the present invention is polymerized in a molar ratio outside the scope of the present invention, the polyimide precursor composition is thawed or left for a long time at room temperature before being used or left in the process of applying the polyimide precursor composition on a support. Also, the effect of suppressing the viscosity change can be exhibited.

In one specific example, the polyimide precursor composition according to the present invention has a viscosity change rate of -20 to + 20%, specifically -15 to + 15%, more specifically -10 to +10, as defined by Equation 2 below. It may be in the range of%.

% Viscosity change = [(3rd viscosity-4th viscosity) / (3rd viscosity)] X 100 (2)

Here, 3rd viscosity is a viscosity immediately after forming a polyimide precursor composition into a support body, and 4th viscosity is a viscosity after 1 hour passed at 25 degreeC after film forming.

In the case of the conventional polyimide precursor composition, since the change rate according to the viscosity immediately after film formation on the support and after 1 hour at 25 ° C. after film formation exceeds the above range, the polyimide precursor is left in the process because of this. The viscosity of the composition may change, which may cause a problem that the thickness of the target polyimide film is not realized.

On the other hand, the polyimide precursor composition of the present invention can be seen that the viscosity change according to the above formula is not as large as the above range, the film forming viscosity stability during the process is very excellent.

<Polyimide film and its manufacturing method>

The present invention comprises the steps of forming a gel film by forming a film of the polyimide precursor composition on a support and dried; And

It can provide a method for producing a polyimide film, comprising the step of curing the gel film.

Specifically, the conventionally known method can be used about the method of imidating the said polyimide precursor composition and manufacturing a polyimide film.

Specific examples of such imidization include a thermal imidization method, a chemical imidization method, or a complex imidation method using the thermal imidization method and the chemical imidization method in combination. Examples thereof include the following non-limiting examples. It will be described in more detail through.

<Thermal imidation method>

The said thermal imidation method removes a chemical catalyst and induces an imidation reaction with heat sources, such as a hot air and an infrared dryer,

Drying the precursor composition to form a gel film; And

The gel film may be heat-treated to obtain a polyimide film.

Here, a gel film can be understood as a film intermediate which has self-support at an intermediate stage with respect to the conversion from polyamic acid to polyimide.

The process of forming the gel film, the precursor composition is cast in the form of a film on a support such as glass plate, aluminum foil, endless stainless belt, or stainless drum, and then the precursor composition on the support is 50 to 200 ℃, details For example, it may be drying at a variable temperature ranging from 80 to 150 ° C.

Accordingly, the gel film may be formed by partial curing and / or drying of the precursor composition, and the formed gel film may be peeled off from the support to obtain a gel film.

In some cases, a process of stretching the gel film may be performed to adjust the thickness and size of the polyimide film obtained in the subsequent heat treatment process and to improve orientation, and the stretching may be performed in the machine transport direction (MD) and the machine transport direction. It may be performed in at least one direction of the transverse direction (TD) with respect to.

The gel film thus obtained may be subjected to a step of fixing to a tenter and then curing at a temperature range of 30 to 500 ° C., specifically, the first heat treatment at 30 to 50 ° C. for 5 to 10 minutes;

A second heat treatment at 180 to 220 ° C. for 25 to 35 minutes; And

Third heat treatment at 440 to 480 ° C. for 35 to 45 minutes to sequentially heat at variable temperature to remove water, residual solvent, etc. remaining in the gel film, and to imidize almost all remaining amic acid groups. , The polyimide film of the present invention can be obtained.

In this case, the first to third heat treatment may be heated at any one or more temperature increase rate selected from the range of 1 ℃ / min to 10 ℃ / min.

In some cases, the polyimide film obtained as described above may be heated to a temperature of 300 to 600 ° C. for 5 to 400 seconds to further cure the polyimide film, and the internal stress may remain in the obtained polyimide film. This may be done under a predetermined tension to relieve the pressure.

<Chemical imidization method>

The chemical imidization method is a method of promoting imidization of an amic acid group by adding a dehydrating agent and / or an imidizing agent to the precursor composition.

As used herein, the term "dehydrating agent" means a substance that promotes a ring-closure reaction through dehydration to polyamic acid, and includes, but is not limited to, aliphatic acid anhydride, aromatic acid anhydride, N, N ' -Dialkylcarbodiimide, halogenated lower aliphatic, halogenated lower patty acid anhydride, aryl phosphonic dihalide, thionyl halide and the like. Of these, aliphatic acid anhydrides may be preferred in view of ease of availability and cost, and non-limiting examples thereof include acetic anhydride (AA), propion acid anhydride, and lactic acid anhydride. These etc. can be mentioned, These can be used individually or in mixture of 2 or more types.

In addition, "imidizing agent" means a substance having an effect of promoting a ring-closure reaction with respect to polyamic acid, and may be an imine-based component such as aliphatic tertiary amine, aromatic tertiary amine, and heterocyclic tertiary amine. Can be. Of these, heterocyclic tertiary amines may be preferable in view of reactivity as a catalyst. Non-limiting examples of heterocyclic tertiary amines include quinoline, isoquinoline, β-picolin (BP), pyridine, and the like, and these may be used alone or in combination of two or more thereof.

It is preferable that the addition amount of a dehydrating agent exists in the range of 0.5-5 mol with respect to 1 mol of amic acid groups in polyamic acid, and it is especially preferable to exist in the range of 1.0 mol-4 mol. In addition, the addition amount of the imidating agent is preferably in the range of 0.05 mol to 2 mol, and particularly preferably in the range of 0.2 mol to 1 mol with respect to 1 mol of the amic acid group in the polyamic acid.

When the dehydrating agent and the imidating agent are less than the above range, chemical imidization is insufficient, cracks may be formed in the polyimide film to be produced, and the mechanical strength of the film may be lowered. In addition, when these addition amounts exceed the above range, imidization may proceed excessively rapidly, in which case it is difficult to cast in the form of a film or the produced polyimide film may exhibit brittle characteristics, which is not preferable. not.

<Complex imidation method>

In connection with the above-mentioned chemical imidation method, the composite imidation method which further performs a thermal imidation method can be used for manufacture of a polyimide film.

Specifically, the complex imidation method includes a chemical imidization process of adding a dehydrating agent and / or an imidizing agent to the precursor composition at a low temperature; And a thermal imidization process of drying the precursor composition to form a gel film and heat treating the gel film.

In performing the chemical imidization process, the type and amount of the dehydrating agent and the imidizing agent may be appropriately selected according to the above-described chemical imidization method.

In the process of forming the gel film, the precursor composition containing the dehydrating agent and / or imidating agent is cast in a film form on a support such as a glass plate, an aluminum foil, an endless stainless belt, or a stainless drum, and then The precursor composition is dried at a variable temperature in the range of 50 to 180 ° C., specifically 80 to 180 ° C. In this process, chemical converting agents and / or imidating agents can act as catalysts so that amic acid groups can be rapidly converted to imide groups.

In some cases, a process of stretching the gel film may be performed to adjust the thickness and size of the polyimide film obtained in the subsequent heat treatment process and to improve orientation, and the stretching may be performed in the machine transport direction (MD) and the machine transport direction. It may be performed in at least one direction of the transverse direction (TD) with respect to.

The gel film thus obtained is fixed in a tenter and then heat treated at the variable temperature described above to remove water, catalyst, residual solvent, etc. remaining in the gel film and to imidize most of the remaining amic acid groups. Polyimide films can be obtained. In such a heat treatment process, the dehydrating agent and / or the imidizing agent may act as a catalyst so that the amic acid group may be rapidly converted to the imide group, thereby enabling high imidation ratio.

In some cases, the polyimide film obtained as described above may be heat-finished at a temperature of 400 to 500 ° C. for 5 to 400 seconds to further cure the polyimide film, and internal stresses may remain in the obtained polyimide film. This may be done under some tension to relieve it.

The present invention can also provide a polyimide film produced by the method for producing a polyimide film.

The polyimide film of the present invention prepared according to the above production method has a thermal decomposition temperature (Td) of 1% by weight of 560 ℃ or more, a thermal expansion coefficient of 5 ppm / ℃ or less, elongation is 15% or more, tensile strength Is 350 MPa or more, and may have a thickness of 10 to 20 μm.

As described above, the method for preparing a polyimide precursor composition according to the present invention comprises preparing a polyamic acid solution by polymerizing a diamine monomer and a dianhydride monomer in an organic solvent in a molar ratio of 1: 0.98 to 0.99. The effect of improving the viscosity stability in the process of apply | coating on the support body of a mid precursor composition can be exhibited.

At the same time, the preparation method according to the present invention comprises the step of heating the polyamic acid solution to 55 to 85 ℃, aging by stirring for 1 to 4 hours, thereby storing at room temperature of the polyimide precursor composition itself The effect of improving stability can be exhibited.

In addition, the polyimide film prepared as described above is excellent in mechanical and thermal properties, and thus may be preferably applied to a flexible circuit board or a display substrate.

Hereinafter, the operation and effects of the invention will be described in more detail with reference to specific examples of the invention. However, these embodiments are only presented as an example of the invention, whereby the scope of the invention is not determined.

<Example 1>

NMP was introduced into a 500 ml reactor equipped with a stirrer and a nitrogen inlet / outlet tube, and the temperature of the reactor was set at 30 ° C., followed by PPD as a diamine monomer and BPDA and PMDA as a dianhydride monomer. Check it. After stirring was continued for 120 minutes while heating up to 40 degreeC under nitrogen atmosphere, the polyamic-acid solution which the viscosity in 23 degreeC shows 7,000 cP was prepared.

Then, stirring was continued for 2 hours while heating up to 80 ° C. under a nitrogen atmosphere, and then cooled to 23 ° C. to show a first viscosity of 4,500 cP, and the diamine monomers and dianhydride monomers were shown in Table 1 below. To prepare a polyimide precursor composition comprising together.

<Examples 2 to 7 and Comparative Examples 1 to 10>

In Example 1, a polyimide precursor composition was prepared in the same manner as in Example 1, except that the monomer and its content, aging status, aging temperature, and aging time were changed as shown in Table 1 below.

Diamine monomer
(mole%) Dianhydride
Monomer
(mole%) Monomer
Molar ratio Aging or not Aging temperature
(℃) Aging time
(minute) PPD
(mole%) PMDA
(mole%) BPDA
(mole%) Example 1 100 68.6 29.4 1: 0.98 O 80 120 Example 2 100 69.3 29.7 1: 0.99 O 80 120 Example 3 100 68.6 29.4 1: 0.98 O 85 120 Example 4 100 68.6 29.4 1: 0.98 O 70 120 Example 5 100 68.6 29.4 1: 0.98 O 60 120 Example 6 100 68.6 29.4 1: 0.98 O 80 240 Example 7 100 68.6 29.4 1: 0.98 O 80 60 Comparative Example 1 100 67.2 28.8 1: 0.96 O 80 120 Comparative Example 2 100 67.9 29.1 1: 0.97 O 80 120 Comparative Example 3 100 70 30 1: 1 O 80 120 Comparative Example 4 100 70.7 30.3 1: 1.01 O 80 120 Comparative Example 5 100 71.4 30.6 1: 1.02 O 80 120 Comparative Example 6 100 68.6 29.4 1: 0.98 O 50 120 Comparative Example 7 100 68.6 29.4 1: 0.98 O 90 120 Comparative Example 8 100 68.6 29.4 1: 0.98 X - - Comparative Example 9 100 68.6 29.4 1: 0.98 O 80 300 Comparative Example 10 100 68.6 29.4 1: 0.98 O 80 30

Experimental Example 1: Evaluation of Storage Stability

The polyimide precursor composition prepared in Examples 1 to 7 and Comparative Examples 1 to 10 was left at room temperature for 7 days. Thereafter, the second viscosity was measured, and a viscosity change was calculated according to Equation 1 below, and is shown in Table 2 below.

Viscosity change = first viscosity-second viscosity (1)

Viscosity was measured by measuring Brookfield viscometer (RVDV-II + P) twice at 50 rpm using 7 scandals at 25 ° C.

First viscosity
(cP) Second viscosity
(cP) Viscosity change
(cP) Example 1 4,500 4,670 +170 Example 2 4,500 4,660 +160 Example 3 4,500 4650 +150 Example 4 4,500 4670 +170 Example 5 4,500 4680 +180 Example 6 4,500 4635 +135 Example 7 4,500 4675 +175 Comparative Example 1 4,500 2300 -2200 Comparative Example 2 4,500 2660 -1840 Comparative Example 3 4,500 4,680 +180 Comparative Example 4 4,500 5,690 +1,190 Comparative Example 5 4,500 8,200 +4,700 Comparative Example 6 4,500 5020 +520 Comparative Example 7 4,500 4650 +150 Comparative Example 8 4,500 7300 +2800 Comparative Example 9 4,500 4670 +170 Comparative Example 10 4,500 5280 +780

Experimental Example 2: Viscosity Stability Evaluation

Bubbles were removed from the polyimide precursor compositions prepared in Examples 1 to 7, 7, and Comparative Examples 10 through a high speed rotation of 1,500 rpm or more. Thereafter, the degassed polyimide precursor composition was applied to the glass substrate using a spin coater.

Immediately after application, the third viscosity of the polyimide precursor composition was measured. Thereafter, the fourth viscosity of the polyimide precursor composition was measured in a state where 1 hour had elapsed at 25 ° C., and a viscosity change rate was calculated according to Equation 2 below, and is shown in Table 3 below.

% Viscosity change = [(3rd viscosity-4th viscosity) / (3rd viscosity)] X 100 (2)

Third viscosity
(cP) Fourth viscosity
(cP) Viscosity change rate
(%) Example 1 4,500 5,135 +14.1 Example 2 4,500 5,120 +13.8 Example 3 4,500 5,110 +13.5 Example 4 4,500 5,135 +14.1 Example 5 4,500 5,160 +14.7 Example 6 4,500 5,105 +13.4 Example 7 4,500 5,155 +14.5 Comparative Example 1 4,500 4,835 +7.4 Comparative Example 2 4,500 5,020 +11.6 Comparative Example 3 4,500 5,910 +31.3 Comparative Example 4 4,500 5,510 +22.4 Comparative Example 5 4,500 5,390 +19.7 Comparative Example 6 4,500 5,300 +17.8 Comparative Example 7 4,500 5,130 +14.0 Comparative Example 8 4,500 4,760 +5.8 Comparative Example 9 4,500 5,115 +13.7 Comparative Example 10 4,500 5,275 +17.2

Referring to Tables 2 and 3, it can be confirmed that the storage stability at room temperature and the viscosity stability in the process are excellent in the examples prepared by the production method of the present invention. On the other hand, it can be seen that the comparative examples do not satisfy at least one of storage stability or viscosity stability.

On the other hand, in Comparative Example 7 prepared by setting the aging temperature higher than the range of the present invention, it can be confirmed that the storage stability at room temperature and the viscosity stability in the process is excellent, as described below, the poly produced through this It can be confirmed that the physical properties of the mid film are reduced.

Experimental Example 3: Physical Property Evaluation

Bubbles were removed from the polyimide precursor compositions prepared in Examples 1 to 7, 7, and Comparative Examples 10 through a high speed rotation of 1,500 rpm or more. Thereafter, the degassed polyimide precursor composition was applied to the glass substrate using a spin coater. After drying in a nitrogen atmosphere at a temperature of 120 ℃ for 30 minutes to prepare a gel film, the gel film is heated to a rate of 2 ℃ / min to 450 ℃, heat treatment at 450 ℃ 60 minutes, up to 30 ℃ Cooling at a rate of 2 ° C./min afforded a polyimide film.

Thereafter, the polyimide film was peeled off from the glass substrate by dipping in distilled water. The thickness of the produced polyimide film was 10 μm. Physical properties of the prepared polyimide film were measured using the following method, and the results are shown in Table 4 below.

(1) thermal expansion coefficient (CTE)

A TA thermomechanical analyzer Q400 was used, and the polyimide film was cut into a width of 2 mm and a length of 10 mm, and then subjected to a tension of 0.05 N in a nitrogen atmosphere at 500 ° C. at a rate of 10 ° C./min. After the temperature was raised to ℃ and cooled again at a rate of 10 ℃ / min was measured the slope of the 350 ℃ section from 100 ℃.

(2) elongation

The polyimide film was cut to 10 mm in width and 40 mm in length, and then elongation was measured by the ASTM D-882 method using an Instron 5564 UTM instrument from Instron.

(3) pyrolysis temperature (TD) of 1% by weight

Thermogravimetric analysis (TA) Q50 model was used, and the polyimide film was heated to 150 ° C. at a rate of 10 min / ° C. under nitrogen atmosphere, and then kept isothermal for 30 minutes to remove moisture. Then, the temperature was raised to 600 ° C. at a rate of 10 min / ° C. to measure the temperature at which 1% weight loss occurred.

(4) tensile strength

The polyimide film was cut to 10 mm in width and 40 mm in length, and then tensile strength was measured by ASTM D-882 method using an Instron 5564 UTM instrument of Instron. The cross head speed at this time was measured under the condition of 5 mm / min.

CTE
(ppm / ℃) Elongation
(%) TD
(℃) The tensile strength
(MPa) Example 1 2.4 18.8 567 365 Example 2 2.4 18.1 568 362 Example 3 2.4 18.2 567 363 Example 4 2.5 18.5 565 362 Example 5 2.4 18.3 566 365 Example 6 2.4 18.1 564 362 Example 7 2.7 18.2 561 370 Comparative Example 1 5.2 9.8 518 312 Comparative Example 2 4.0 11.5 524 325 Comparative Example 3 2.0 19.7 572 375 Comparative Example 4 2.1 12.5 560 344 Comparative Example 5 6.9 7.5 558 292 Comparative Example 6 2.1 17.3 566 368 Comparative Example 7 5.5 14.8 525 314 Comparative Example 8 2.5 17.1 556 341 Comparative Example 9 5.1 16.5 541 337 Comparative Example 10 2.5 17.8 559 345

Referring to Table 4, in the case of the examples prepared by the manufacturing method of the present invention it can be seen that both excellent mechanical and thermal properties. On the other hand, it can be seen that the comparative examples do not satisfy at least one of mechanical or thermal properties.

On the other hand, in Comparative Example 3 prepared from a polyimide precursor composition obtained by polymerizing a diamine monomer and a dianhydride monomer in a 1: 1 molar ratio, it can be confirmed that the physical properties are excellent, but as described above, the viscosity of the polyimide precursor composition It can be confirmed that the stability is not excellent.

Although described above with reference to embodiments of the present invention, those skilled in the art to which the present invention pertains, it will be possible to make various applications and modifications within the scope of the present invention based on the above contents.

Claims (18)

(a) polymerizing a diamine monomer and a dianhydride monomer in an organic solvent in a molar ratio of 1: 0.98 to 0.99 to prepare a polyamic acid solution; And
(b) warming the polyamic acid solution to 55 to 85 ° C. and stirring for 1 to 4 hours, aging;
Method for producing a polyimide precursor composition, the viscosity change defined by the following formula 1 is in the range of -200 cP to +200 cP:
Viscosity change = first viscosity-second viscosity (1)
Here, a 1st viscosity is an initial viscosity of a polyimide precursor composition at 25 degreeC, and a 2nd viscosity is a viscosity after 7 days passed at 25 degreeC. The method of claim 1,
In the step (a), the polymerization reaction is carried out at 20 to 40 ℃, method of producing a polyimide precursor composition. The method of claim 1,
In the step (b), the polyamic acid solution is heated to 60 to 80 ℃, and stirred for 2 to 3 hours, a method for producing a polyimide precursor composition. The method of claim 1,
(C) further comprising the step of cooling the polyamic acid solution aged in step (b) to 10 to 30 ℃, manufacturing method of a polyimide precursor composition. The method of claim 1,
The diamine monomers are 1,4-diaminobenzene (PPD), 1,3-diaminobenzene (MPD), 2,4-diaminotoluene, 2,6-diaminotoluene and 3,5-diaminobenzoic acid At least one selected from the group consisting of acid (DABA),
The dianhydride monomers are pyromellitic dianhydride (PMDA), 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) and 2,3,3', 4 ' -Biphenyl tetracarboxylic dianhydride (a-BPDA) comprising at least one member selected from the group consisting of, a method for producing a polyimide precursor composition. A polyimide precursor composition prepared by the method according to claim 1. delete The method of claim 1,
The first viscosity is 3,000 to 8,000 cP, the method for producing a polyimide precursor composition. The method of claim 6,
The polyimide precursor composition comprises 10 to 15% by weight solids based on the total weight, polyimide precursor composition. The method of claim 6,
The polyamic acid included in the polyimide precursor composition has a poly dispersity index of 1.5 to 2.0 of a weight average molecular weight to a number average molecular weight. Preparing a gel film by forming a polyimide precursor composition according to claim 6 on a support and drying the composition; And
Comprising curing the gel film. The method of claim 11,
Method for producing a polyimide film, the viscosity change rate of the polyimide precursor composition defined by the following formula 2 is in the range of -15 to + 15%:
% Viscosity change = [(3rd viscosity-4th viscosity) / (3rd viscosity)] X 100 (2)
Here, 3rd viscosity is a viscosity immediately after forming a polyimide precursor composition into a support body, and 4th viscosity is a viscosity after 1 hour passed at 25 degreeC after film forming. The method of claim 11,
The curing is sequentially
First heat treatment at 30 to 50 ° C. for 5 to 10 minutes;
A second heat treatment at 180 to 220 ° C. for 25 to 35 minutes; And
And a third heat treatment at 440 to 480 ° C. for 35 to 45 minutes. The method of claim 13,
The first heat treatment to the third heat treatment is a method of producing a polyimide film is heated at any one or more temperature increase rate selected from the range of 1 ℃ / min to 10 ℃ / min. A polyimide film prepared by the manufacturing method according to claim 11. The method of claim 15,
Pyrolysis temperature (Td) of 1% by weight is 560 ℃ or more,
The coefficient of thermal expansion is 5 ppm / ° C or less,
Elongation is more than 15%,
Tensile strength is over 350 MPa,
The polyimide film having a thickness of 10 to 20 μm. An electronic device comprising the polyimide film of claim 15. The electronic device of claim 17, wherein the electronic device comprises a flexible printed circuit board or a display substrate.